Has the Earth crossed its “planetary limits”?

Planet Earth seen from the Moon, in a photo released by NASA in 1968.

This post is taken from the newsletter ” Human warmth “, sent every Tuesday at 12 p.m. Every week, journalist Nabil Wakim, who hosts the Human Heat podcast, answers Internet users’ questions about the climate challenge. You can register for free here:

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The question of the week

“Hello, in the episode of the podcast “Chaleur humaine” with Timothée Parrique, he talks about the fact that our economic model is not compatible with planetary limits. I had never heard of this concept. (…) Is it scientifically based? What are these limits, and what happens if they are crossed? » Question asked by Marta at chaud [email protected]

My answer : Dear Marta, thank you for this question which forced me to delve into a subject that I did not know well. Yes, the concept of “planetary boundaries” is scientifically established. This is a reading grid for measuring the impacts of human activity on the planet and understanding whether we are still in a “safe living space for humanity”. The idea is that we are not at all in the right direction, but that looking at these different limits allows us to understand and act.

1 – Who had this crazy idea?

The concept of planetary boundaries comes from an international study carried out in 2009 (you can find the scientific article here). It sets nine limits that must not be crossed so that the earth’s ecosystem continues to function in a way that is livable for us humans. Swedish researcher Johan Rockström explains in an educational way this concept in this TED video, viewed nearly 2 million times.

This scientific work is based on the fact that the balance of the earth over the last ten thousand years has allowed living conditions very favorable to the development of humanity. But human activities have such an impact on this ecosystem that they can make the planet uninhabitable, by destabilizing the space in which we live. These different limits of course have important interactions between them. The question could be asked as follows: what are the boundaries that should not be crossed?

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